Growth analysis of Pimpinella anisum under different irrigation regimes and amounts of super absorbent polymer

ABSTRACT: In order to decrease the effect of water stress on anise plant (Pimpinella anisum), a factorial experiment was conducted based on randomized complete block design with four replications in 2009. Treatments were irrigation regimes (irrigation after 40, 80, 120 and 160 mm evaporation from pan class A) and super absorbent polymer (0, 60, 120, 180 and 240 kg/ha). Results of plant growth analysis indicated that the biomass (Total Dry Weight) had a slow raise till 806 Growth Degree-Days (GDDs)=55 Days after Sowing (DAS). Then a fast increase till 1392 GDDs=85 DAS for irrigation after 80, 120 and 160 mm, and 670 GDDs=100 DAS for irrigation after 40 mm evaporation. Quadratic relationship between Crop Growth Rate (CGR) and GDDs was observed in all experimental treatments. At the end of growth, after 85 days, values of CGR were come closer. Linear function obtained between Relative Growth Rate and GDDs, indicated a descending trend of during growth season. There was a respective reduction of biomass, CGR and RGR obtained from irrigation after 80, 40, 120 and 160 mm evaporation. Leaf Area Ratio (LAR) had a binomial relation with GDDs in all experimental treatments. Anise plants irrigated after 40 and 80 mm evaporation from pan obtained the highest and same values of LAR, and it was dropped in wider irrigation intervals. Despite of descending trends in Leaf Area Index (LAI) by irrigation after 80, 40, 120 and 160 mm evaporation, a few distances was observed between LAI obtained from irrigation after 80 and 40 mm evaporation. A similar change of total dry weight, CGR, RGR, LAR and LAI with super absorbent treatments was occurred as well as irrigation. A descending trend of biomass, CGR, RGR, LAR and LAI was occurred with 240, 180, 120, 60 and 0 kg/ha super absorbent.